Image fusion-based low-dose CBCT enhancement method for visualizing miniscrew insertion in the infrazygomatic crest

Digital dental technology covers oral cone-beam computed tomography (CBCT) image processing and low-dose CBCT dental applications. A low-dose CBCT image enhancement method based on image fusion is proposed to address the need for subzygomatic small screw insertion. Specifically, firstly, a sharpening correction module is proposed, where the CBCT image is sharpened to compensate for the loss of details in the underexposed/over-exposed region. Secondly, a visibility restoration module based on type II fuzzy sets is designed, and a contrast enhancement module using curve transformation is designed. In addition to this, we propose a perceptual fusion module that fuses visibility and contrast of oral CBCT images. As a result, the problems of overexposure/underexposure, low visibility, and low contrast that occur in oral CBCT images can be effectively addressed with consistent interpretability. The proposed algorithm was analyzed in comparison experiments with a variety of algorithms, as well as ablation experiments. After analysis, compared with advanced enhancement algorithms, this algorithm achieved excellent results in low-dose CBCT enhancement and effective observation of subzygomatic small screw implantation. Compared with the best performing method, the evaluation metric is 0.07-2 higher on both datasets. The project can be found at: https://github.com/sunpeipei2024/low-dose-CBCT .

The Spatial Relationship Between Coronoid Process and Zygomatic Complex After Reduction Malarplasty

BACKGROUND

Reduction malarplasty presents challenges in terms of postoperative complications, particularly limited mouth opening. Excessive inward displacement of the zygomatic complex can impinge on the coronoid process resulting in restricted mouth opening. This study aimed to assess the spatial relationship between the coronoid process and the zygomatic complex after reduction malarplasty.

METHODS

A retrospective study was conducted, including consecutive patients underwent reduction malarplasty. Radiological measurements were performed before surgery and during the final follow-up, including the coronoid-condylar index, distance between the coronoid process and zygomatic complex, and thickness and density of the temporal and masseter muscles. Clinical and radiographic data were recorded and analyzed.

RESULTS

A total of 159 female patients were included with an average age of 28.1 years and a mean follow-up of 6.7 months. The mean coronoid-condylar index was 1:1.4, ranging from 1:0.6 to 1:2.6. Following surgery, the distances between the coronoid process and the anterior zygoma decreased by approximately 1 mm. Additionally, the postoperative distance between the highest point of the coronoid process and the zygomatic arch decreased by around 4 mm horizontally and changed approximately 1 mm vertically. No significant changes were observed in the thickness and density of the temporal and masseter muscles after surgery.

CONCLUSIONS

Reduction malarplasty led to a slight decrease in the distance between the coronoid process and the zygoma. The operation generally resulted in proximity between the highest point of the coronoid process and the zygomatic arch. However, we believe that common reduction malarplasty rarely leads to osseous impingement.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Volume Redistribution of the Buccal Fat Pad After Reduction Malarplasty

BACKGROUND

During reduction malarplasty, cheek bulging could be found immediately after zygomatic complex is moved inwards, backwards and upwards. As patient is in the supine position during surgery, the effect of gravity is eliminated, so the only reason for the bulge is the redistribution of the soft tissue in the deep facial spaces. The buccal fat pad, with its main body behind the zygomatic arch and buccal extension in the cheek area, is most likely to be responsible for the bulge.

METHODS

3D buccal extension models were reconstructed from preoperative and long-term follow-up CT images and the volume measured. By comparing the pre- and postoperative 3D models, the shape deviation of the buccal extension and facial soft tissue can be identified.

RESULTS

Eleven patients (22 buccal extensions) met the inclusion criteria. Compared with the preoperative buccal extension volume, the postoperative volume increased significantly. By comparing the reconstructed models, the buccal extension volume increase with anteroinferior protrusion can be visually detected, and cheek bulging was clearly identified on the lower face. The bulging area coincided with the projection of the buccal extension on the skin surface.

CONCLUSIONS

Reduction malarplasty may cause volume redistribution of the buccal fat pad. Therefore, preoperative assessment of the size of the buccal fat pad based on CT images is recommended. The buccal extension volume increase with anteroinferior protrusion is an important cause of postoperative cheek bulging and should be considered during treatment.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Successful Reduction of Unilateral Zygoma Fracture Following Bilateral Malar Reduction Surgery

Malar reduction surgery can increase its susceptibility to fractures in case of trauma. Patients who had malar reduction surgery and sustained a zygoma fracture pose unique challenges for treatment and management. This is a case of a 28-year-old female patient who presented with a unilateral zygoma fracture following bilateral malar reduction and augmentation rhinoplasty 6 years ago. Physical examination revealed a clicking sound when opening the mouth at the right zygomatic buttress and a depressed preauricular area, suggesting arch fracture. Computed tomography imaging demonstrated a loosened screw at the right zygomatic buttress and a depressed arch fracture. She wanted to remove all plates and treat her right fractured zygoma with absorbable materials. Through the bilateral intraoral incisions, the authors removed the plates and screws and reduced the depression with the Langenbeck elevator through the same right intraoral incision without fixation. The reduction was well-maintained without complications based on postoperative plain x-rays 1 month after surgery. She reported that the pain was mostly gone and that she did not hear any abnormal sounds when opening her mouth after the surgery. In this case, if the zygomaticomaxillary buttress is minimally displaced, but the zygomatic arch fracture is significantly depressed, the authors believe that fracture reduction with only an intraoral incision would be enough to achieve an optimal outcome. If the plates and screws used in the previous malar reduction are not well maintained, it may be necessary to remove them.

Three-dimensional radiographic assessment of different fixation methods stability after l-shaped osteotomy reduction malarplasty: A comparative retrospective study

BACKGROUND

Reduction malarplasty (RM) is a common facial contouring procedure among Orientals. Currently, fixation methods selection and placement vectors are controversial. Therefore, this study aimed to evaluate the effect of different zygomatic complex fixation methods on surgical outcomes stability after RM.

MATERIALS AND METHODS

In this retrospective study, 60 consented patients (120 operated zygoma) who met inclusion criteria were included. ITK-SNAP and 3D Slicer software were used to measure the displacement of the zygomatic complex using postoperative CTs (T1: one week and T2: six months). The region of interest included zygomatic body fixation methods (ZBFm), namely: two bicortical screws (2LS); an l-shaped plate with one bicortical screw (LPLS); an l-shaped plate with short-wing on the zygoma (LPwZ) and on the maxilla (LPwM), combined with zygomatic arch fixation methods (ZAFm), including Mortice-Tenon (MT); 3-hole plate (3HP); and short screw (SS). ANOVA test was used to compare the displacement values among ZBFm/ZAFm combinations.

RESULTS

The 2LS and LPLS groups showed lower displacement than the single l-shaped plate (P< 0.001, P = 0.001), which performed better when the short-wing was fixated on the maxilla (0.9 ± 0.4 mm and 1.2 ± 0.6 mm respectively).

CONCLUSION

After RM, the two-bridge fixation methods (2LS and LPLS) provide better stability than the single l-shaped plate. All ZAF methods showed similar stability when combined with 2LS or LPLS as zygomatic body fixation methods.

Longitudinal reactions of maxillary sinus in patients treated with multiple zygomatic implants: A modified radiographic evaluation with clinical follow-up

OBJECTIVES

To investigate the effects of zygomatic implant placement on the maxillary sinus using radiographic and clinical indicators.

METHODS

Patients with an atrophic maxilla who underwent zygomatic implant placement were included. The thickness and morphology of the Schneiderian membrane (SM), infundibular obstruction, and posterior bone wall of the maxillary sinus were analyzed. The generalized estimating equation and chi-square tests were performed to compare the measurements.

RESULTS

Fifty patients with 100 maxillary sinuses were included. In total, 148 zygomatic implants and 105 regular implants were placed in the maxilla. Overall, the mean pre- and postoperative SM thickness was 2.79 ± 3.26 mm and 3.97 ± 5.45 mm, respectively (p = 0.063). In sinuses with two zygomatic implants, the SM thickness increased significantly from 2.12 ± 2.14 mm preoperatively to 4.07 ± 6.14 mm postoperatively (p = 0.026). The number of sinuses with type IV morphology (fully radiopaque) increased from zero preoperatively to six (13%) postoperatively. Sinuses with a single zygomatic implant showed no difference in the pre- and postoperative SM thickness. Postoperatively, six sinuses had infundibulum obstructions. Postoperative osteitis of the bilateral sinuses was found in two patients.

CONCLUSIONS

We have proposed a new imaging evaluation method and system for evaluating the maxillary sinus response. Preoperative infundibulum obstruction combined with mucosal thickening and double zygomatic implant placement are more likely to induce postoperative maxillary sinus mucositis and osteitis.

Stress distribution and displacement with four different types of MARPE on craniofacial complex: A three-dimensional finite element analysis

BACKGROUND

Various designs of mini-implants assisted rapid palatal expander (MARPE) appliances can impact treatment effectiveness through their biomechanical effects. The purpose of the study was to study the stress distribution and displacement with four different designs of the MARPE appliance on the craniofacial complex.

METHODS

A 3D finite element model of the craniofacial complex was created from CBCT DICOM data, comprising four distinct groups. Each group consisted of one 4-hole expansion screw positioned between the second premolar and first molar in all models. Group 1 used four single-cortical mini-implants (1.5×8mm) engaging only the palatal cortex. Group 2 employed four mini-implants (1.5×11mm) engaging both the palatal and nasal cortices. Group 3 had monocortical implants on the palatal slopes, while Group 4 was similar to group 3 with implants in the acrylic wings. Comparisons between groups were made for anchorage (groups 1 and 2), mini-implant position (groups 1 and 3) and surface effect (groups 3 and 4). Von Mises stresses and displacements at various skeletal and dental points were evaluated using ANSYS software.

RESULTS

The highest stresses were observed in the maxillary, pterygoid and zygomatic bones, as well as in the mid- palatal suture in all four groups. Downward and forward rotation of the craniofacial complex was noted. Group 2 showed greater skeletal expansion than group 1. Among groups 1 and 3, group 3 showed a better stress distribution. Group 4 showed less dentoalveolar rotation than group 3.

CONCLUSIONS

The MARPE appliances had an impact on the craniofacial complex with stresses on the mid-palatal suture, maxillary bone, pterygoid bones and anterior teeth. Clockwise rotation of the maxilla, zygomatic bones and dentition was noted, while the pterygoid bones and pterygoid suture were displaced backwards. MARPE with bicortical anchorage produces better skeletal expansion. Placing implants on the palatal slopes with acrylic wings results in better skeletal expansion with less clockwise rotation of the dentition.

Treatment of Sagittal Fracture of the Zygomatic Arch Root

A sagittal fracture at the temporal root of the zygomatic arch (ZAR) often occurs as a component of zygomaticomaxillary complex (ZMC) fractures. However, this area is difficult to access, and anchorage is limited due to the unstable structure around it. Therefore, a preauricular approach using single-screw fixation is proposed, and this study reports its results and usefulness. Forty-four patients with sagittal fractures of ZAR occurring with ZMC fractures were evaluated from 2012 to 2021. Open reduction and internal fixation were performed on all patients with ZMC fractures. Closed reduction using Dingman incision and external finger pressure in group A (indirect approach; 30 patients) and single-screw fixation using a preauricular approach in group B (direct approach; 14 patients) were performed to address sagittal fractures in ZAR. For single-screw fixation, the additional mean operation time was 11.34±3.25 minutes. On postoperative 3-dimensional computed tomography and plain radiographs, group B showed more accurate reduction and less deformity and trismus ( P <0.05). Moreover, a normal diet was initiated more quickly in group B than in group A ( P <0.05). Some cases in group A showed nonunion or malunion. This study revealed that a direct approach (group B) toward sagittal fractures of ZAR is recommended due to more accurate results and fewer complications than those observed with the indirect approach (group A). Moreover, the total operation time and complications may be lesser than those with the bicoronal approach.

The Value of Intraoperative Computed Tomography in the Treatment of Zygomatic Complex Fractures

BACKGROUND

Due to the complex anatomical morphology and lack of anatomic markers on the surface of zygomatic complex (ZMC), the treatment results of ZMC fractures are often suboptimal.

PURPOSE

The study aimed to evaluate the effectiveness of intraoperative computed tomography (ICT) in the treatment of unilateral ZMC fractures, and further study the feasibility of ICT to replace early postoperative Computed Tomography (CT).

STUDY DESIGN, SETTING, AND SAMPLE

The investigators designed a retrospective cohort study. Adult patients who underwent surgery with unilateral ZMC fractures were enrolled.

PREDICTOR VARIABLE

According to whether intraoperative CT was used, the subjects were divided into the ICT group and the control group (without ICT).

MAIN OUTCOME VARIABLES

Five distances and 3 angles representing bilateral ZMC symmetry were main outcome variables. The differences of outcome variables were compared between the 2 groups and the indices of ICT group were further compared with their postoperative indices.

COVARIATES

Demographics (eg age), etiology (eg traffic injury), dysfunction (eg diplopia), and surgical approach (eg vestibular incision) were collected as covariates while we conducted clinical investigation, examination, and implementation.

ANALYSES

The data were analyzed using independent-samples t test, paired-samples t test, Mann-Whitney U test, and χ2 test. P value < .05 was considered statistically significant.

RESULTS

A total of 60 patients (18 to 59 years) were enrolled in this study. All median values of the measurements in the ICT group were smaller than those in the control group, and the differences of horizontal displacement distance (0.56 vs 1.02 mm), anteroposterior displacement distance (1.69 vs 2.34 mm, 0.90 vs 2.35 mm), horizontal angle of bilateral zygomatic arch (2.31 vs 4.19°), and horizontal angle of bilateral zygomatic process (1.77 vs 2.94°) were significantly different between the 2 groups with P value < .05. Moreover, there was no statistically significant difference in all indices between the intraoperatively and postoperatively injured sides in the ICT group.

CONCLUSIONS

ICT can improve the treatment outcomes of ZMC fractures by evaluating the fracture reduction adequacy during surgery. Moreover, ICT can replace early postoperative CT.

Quantitative assessment of image artifacts from zygoma implants on CBCT scans using different exposure parameters

This study was aimed at quantifying artifacts from zygoma implants in cone-beam computed tomography (CBCT) images using different exposure parameters. Two cadaver heads, one with two zygoma implants on each side and the other for control, were scanned using 18 different exposure parameters. Quantitative analysis was performed to evaluate the hypodense and hyperdense artifact percentages calculated as the percentage of the area. Hyperdense artifacts and hypodense artifacts were detected, followed by the calculation of the hyperdense and hypodense artifact percentages in the image. In the qualitative analysis of the artifacts, the scores used were as follows: absence (0), moderate presence (1), or high presence (2) for hypodense halos, thin hypodense lines, and hyperdense lines. Artifact analysis was performed qualitatively and quantitatively using the post-hoc Tukey and Two-way ANOVA tests. As a result, in the qualitative analyses, zygoma implants showed a significant difference compared to the control group with regard to hyperdense and hypodense artifacts (p < 0.05). There was a significant difference between the means according to the FOV size arithmetic averages (p < 0.05). In terms of voxel size, the difference was found to be significant, where 400 microns showed the highest hypodense artifact while 200 microns showed the lowest hypodense artifact. In conclusion, hypodense and hyperdense artifacts were significantly higher in cadavers with zygoma implants than in controls. As FOV and voxel size increase, more hypodense artifacts are produced by zygoma implants so smaller FOV and voxel sizes should be used to prevent poor image quality of adjacent teeth.

Precise Coronoidectomy and Zygomatic Arch Reduction for Unilateral Hyperplasia of the Coronoid Process (Jacob's Disease) via Computer-aided Design and Manufacture

Jacob disease is the new formation of a pseudo-joint between both of enlarged coronoid process and even zygomatic arch. A 23-year-old female patient with facial asymmetry and limited mouth opening was reported. Computed tomography images showed the classic symptom of Jacob disease with a mushroom-shaped tumor mass from the coronoid process a pseudoarthrosis joint with zygomatic arch. Coronoidectomy and zygomatic arch reduction were planned to operate based on computer-aided design/computer-aided manufacturing. During the actual operation, the excision of coronoid process and reconstruction of zygomatic arch were all navigated by 3-dimensional-printed surgical templates as designed through an intraoral approach. As a result, the enlarged coronoid process was smoothly removed without sequela and mouth opening along with facial symmetry were successfully improved. The authors suggested that computer-aided design/computer-aided manufacturing should be considered as an auxiliary technique to shorten operation time and enhance surgical accuracy.

Intraosseous venous malformation of the zygoma: Case report and pooled analysis

The objective of this study is to provide a comprehensive summary of the clinical and radiological features of zygomatic intraosseous venous malformations (IVM), as well as its treatment strategies. The aim is to establish preoperative diagnostic bases that will aid in the identification of zygomatic IVM and facilitate the implementation of effective treatment. Four cases of pathologically diagnosed zygomatic IVM with typical clinical and radiological features were reported. They exhibited comparable clinical and radiological features, and the En bloc excision and reconstruction yielded satisfactory outcome. Pooled data analysis was performed with additional 74 cases collected from 63 previous studies. The results revealed a higher incidence of zygomatic IVMs in middle-aged females, with swelling, pain and ocular dysfunction being the typical clinical manifestations. The characteristic radiological features of these lesions were well-defined, round bony structures with specific internal trabecular patterns. A diagnostic flow-chart assisting the differential diagnosis of IVM was established. En bloc excision was deemed the most advantageous treatment option, as it presented minimal risk of haemorrhaging and no instances of recurrence. The decision to pursue reconstruction was contingent upon the extent of the defect. Alloplastic material has emerged as the most frequently employed reconstruction material in recent reports. The summarized characteristics of zygomatic IVM and the proposed diagnostic and treatment strategies, derived from the pooled analysis of reported cases, may help to improve diagnosis and management in further clinical practice.

A novel technique to quantify bone-to-implant contact of zygomatic implants: a radiographic analysis based on three-dimensional image registration and segmentation

OBJECTIVES

The purpose of this study is to establish a novel, reproducible technique to obtain the BIC area (BICA) between zygomatic implants and zygomatic bone based on post-operative cone-beam computed tomography (CBCT) images. Three-dimensional (3D) image registration and segmentation were used to eliminate the effect of metal-induced artifacts of zygomatic implants.

METHODS

An ex-vivo study was included to verify the feasibility of the new method. Then, the radiographic bone-to-implant contact (rBIC) of 143 implants was measured in a total of 50 patients. To obtain the BICA of zygomatic implants and the zygomatic bone, several steps were necessary, including image preprocessing of CBCT scans, identification of the position of zygomatic implants, registration, and segmentation of pre- and post-operative CBCT images, and 3D reconstruction of models. The conventional two-dimensional (2D) linear rBIC (rBICc) measurement method with post-operative CBCT images was chosen as a comparison.

RESULTS

The mean values of rBIC and rBICc were 15.08 ± 5.92 mm and 14.77 ± 5.14 mm, respectively. A statistically significant correlation was observed between rBIC and rBICc values ([Formula: see text]=0.86, p < 0.0001).

CONCLUSIONS

This study proposed a standardized, repeatable, noninvasive technique to quantify the rBIC of post-operative zygomatic implants in 3D terms. This technique is comparable to conventional 2D linear measurements and seems to be more reliable than these conventional measurements; thus, this method could serve as a valuable tool in the performance of clinical research protocols.

Application of Computer-Aided Design and Individualized Templates for Bilateral Zygomaticomaxillary Complex Fractures

PURPOSE

Reduction of the bilateral zygomaticomaxillary complex (ZMC) fracture with individualized templates based on computer- aided surgical simulation system. To evaluate the practicality and accuracy of this approach in the treatment of bilateral ZMC fracture.

METHODS

Sixteen patients with bilateral ZMC fractures were collected to create a study model. The authors reconstruct the ZMC on one side via the three-dimensional (3D) model, and then mirrored to the opposite side. Multiple individualized templates were made based on the 3D model, and used as intraoperative guidance to reduce fractures. After surgery, the facial symmetry and the position of zygoma were observed. The mouth opening, pupil level, and sensation of infraorbital nerve were evaluated. Some mark points on zygoma were measured and the postoperative horizontal asymmetry rate (H) was calculated. Besides, orbital height and width were measured.

RESULTS

For all patients, the position of bilateral ZMC was basically restored. The patients with restriction of mouth opening all recovered to normal. The H values were less than 3.0% at all mark points. There was almost no difference in bilateral orbital width and height. Meanwhile, there was no significant difference between the preoperative measurements of the ideal virtual 3D model and the postoperative measurements of patients.

CONCLUSIONS

The study proves that application of computer-aided design and individualized templates can accurately guide the reduction operation of ZMC fracture, restore the ideal shape of ZMC, and obtain good facial symmetry.

Intramuscular lipoma of the temporalis muscle extending to the infratemporal fossa: surgical pitfalls and short literature review

Lipomas are benign tumours of mesenchymal origin, representing one of the most common tumours of the body. They are often observed between the fourth and the sixth decade of life and in 13% of the cases they occur in the head and neck region. In case of symptoms, surgical removal is the treatment of choice; when the formation involves the temporal region, the surgical approach is often challenging due to the presence of the neurovascular structures, such as the temporalis branch of the facial nerve and their potential extension to the nearby structures under the zygomatic arch to either the infratemporal fossa or the buccal region. Recurrence can occur frequently only if there is incomplete removal of lipoma. In this paper, the authors discuss surgical pitfalls of a very rare case of a large-sized symptomatic lipoma extended to the infratemporal and pterygomaxillary fossa, surgically removed via trans-zygomatic hemicoronal approach.

Quantitative Morphologic Analysis of Cranial Vault in Twist1+/- Mice: Implications in Craniosynostosis

BACKGROUND

The haploinsufficiency in the TWIST1 gene encoding a basic helix-loop-helix transcription factor is a cause of one of the craniosynostosis syndromes, Saethre-Chotzen syndrome. Patients with craniosynostosis usually require operative release of affected sutures, which makes it difficult to observe the long-term consequence of suture fusion on craniofacial growth.

METHODS

In this study, we performed quantitative analysis of morphologic changes of the skull in Twist1 heterozygously-deleted mice (Twist1+/-) with micro-computed tomographic images.

RESULTS

In Twist1+/- mice, fusion of the coronal suture began before postnatal day 14 and progressed until postnatal day 56, during which morphologic changes occurred. The growth of the skull was not achieved by a constant increase in the measured distances in wild type mice; some distances in the top-basal axis were decreased during the observation period. In the Twist1+/- mouse, growth in the top-basal axis was accelerated and that of the frontal cranium was reduced. In the unicoronal suture fusion mouse, the length of the zygomatic arch of affected side was shorter in the Twist1+/- mouse. In one postnatal day 56 Twist1+/- mouse with bilateral coronal suture fusion, asymmetric zygomatic arch length was identified.

CONCLUSION

The authors'results suggest that measuring the length of the left and right zygomatic arches may be useful for early diagnosis of coronal suture fusion and for estimation of the timing of synostosis, and that more detailed study on the growth pattern of the normal and the synostosed skull could provide prediction of the risk of resynostosis.

CLINICAL RELEVANCE STATEMENT

The data from this study can be useful to better understand the cranial growth pattern in patients with craniosynostosis.

Digital localization of osteotomy position in prominent zygomatic arch

The study aimed at introducing a digital method of locating the osteotomy position of the zygomatic arch during surgery and analyze the accuracy of this method. Patients with a prominent zygomatic bone who underwent zygomatic arch osteotomy and reduction in the orthognathic surgery department of our hospital were selected. Preoperative and postoperative computed tomography (CT) data of the patients were imported into modeling and analysis software Mimics 23.0 in DICOM format to construct 3D models of the zygomatic bone and zygomatic arch region. The data were obtained by locating the simulated osteotomy position of the zygomatic arch before the surgery, applying the digitally modeled osteotomy position of the zygomatic arch during the surgery, and locating the actual osteotomy position of the zygomatic arch after the surgery. The accuracy of the experimental method was verified by matching the preoperative simulation data with the postoperative osteotomy data. A Wilcoxon rank sum test was performed to compare the 20 cases' osteotomy positions obtained by preoperative simulation with the actual postoperative position. There was no significant difference in zygomatic arch osteotomy position between the preoperative simulation and the real postoperative position (Z=-1.867, P=0.062). The digital method to locate the zygomatic arch osteotomy seems to show an acceptable accuracy to achieve the proper osteotomy position and, therefore, should adopted whenever appropriate.

"Digital Simulation of Osteotomy Reduction of a Prominent Zygomatic Arch"

OBJECTIVE

To analyze the value of simulated surgery in predicting the outcome of individualized surgical reduction of a prominent zygomatic arch.

METHODS

Computed tomography data were obtained from the electronic records of 15 patients who underwent surgery at Tianjin Stomatological Hospital for prominent zygoma. The data were imported into Mimics 23.0. Left and right three-dimensional (3D) zygoma models were created through standard procedures. In the 3D models, a wedge-shaped cut of the zygomatic bone was pushed inward, and the osteotomy position of the zygomatic arch was taken as a variable to simulate the reduction malarplasty. The reduction effect was calculated from the simulated movement of the fracture end of the zygomatic arch from internal pushing forces. Stable versus high-efficiency internal pushing areas were defined based on the amount of movement. Mean values with 95% confidence intervals (CI) were calculated for the areas data.

RESULTS

The anterior edge of the stable internal pushing osteotomy area was located in front of the articular tubercle point (95% CI: 10.64-11.89 mm). The posterior edge of the stable internal pushing area was located in front of the articular tubercle point (95% CI: 7.8-9.13 mm). The posterior edge of the high-efficiency internal pushing area was located in front of the articular tubercle point (95% CI: 4.7-5.73 mm).

CONCLUSION

Stable and high-efficiency internal pushing areas were detected above the zygomatic arch. The simulation showed that osteotomy in these areas can provide different degrees of zygomatic arch reduction.

Identification of the Pathway and Appropriate Use of Four Zygomatic Implants in the Atrophic Maxilla: A Cross-Sectional Study

PURPOSE

This cross-sectional study aimed to identify and characterize the pathway for appropriate placement of four zygomatic implants in the severely atrophic maxilla and to group the anatomical variations of the osteotomy trajectory for anterior zygomatic implants.

MATERIALS AND METHODS

CBCT images of patients presenting indications for the use of four zygomatic implants to withstand a maxillary rehabilitation were reviewed. Cross-sectional planes corresponding to the implant trajectories, designed according to a zygoma anatomy-guided approach for implants placed in the anterior and posterior maxilla, were assessed separately. The relationship of the implant osteotomy trajectory with the correlated residual alveolar bone, nasal and sinus cavities, maxillary wall, and zygomatic bone anatomies was established.

RESULTS

The study population included 122 globally recruited patients, with 488 zygomatic implants, 244 of which had their starting point on the anterior incisor-canine area and 244 on the posterior premolar-molar area. The anatomy of the osteotomy path designed for the anterior implants ("A") was named and grouped into five assemblies from zygomatic anatomy-guided ZAGA A-0 to A-4, representing 2.9%, 4.5%, 19.7%, 55.7%, and 17.2% of the studied sites. Percentages for posterior implant ("P") trajectories of the osteotomy were grouped and named as ZAGA P-0 to P-4, representing 5.7%, 10.2%, 8.2%, 18.4%, and 57.4% of the sites, respectively. Approximately 70% of the population presented anatomical intra-individual differences.

CONCLUSION

The trajectory of the zygomatic implant followed different anatomical pathways depending on its coronal point being anteriorly or posteriorly located, which justifies a new zygoma anatomy-guided approach classification for anteriorly placed zygomatic implants. Topographic characteristics of the anatomical structures that are cut by an anterior oblique plane joining the lateral incisor-canine area to the zygomatic bone, representing the planned anterior osteotomy path in a quadruple-zygoma indication, have not been previously reported. Adaptation of surgical procedures and implant sections/designs to individual patients' anatomical characteristics is essential to reduce early and long-term complications.

Radiologic Analysis of Malar Arch Movement in Reduction Malarplasty Without Bony Resection

BACKGROUND

Reduction malarplasty has been popular among Asians with a wide facial width. In general, malar setback after bony resection is regarded as the standard objective of reduction malarplasty. However, unnecessary bony resection may lead to various postoperative complications. Therefore, we suggest the use of reduction malarplasty without bony resection to achieve a similar narrowing effect of the facial width, based on radiographic analysis of malar arch movement.

PATIENTS AND METHODS

This retrospective study analyzed 48 patients with a wide midface who underwent reduction malarplasty between September 2018 and December 2019. We included 40 cases of advancement repositioning malarplasty (AR) without bony resection and 8 cases of setback reduction malarplasty (SR) with bony resection. The three-dimensional position of the malar arch expressed by coordinates (x, y, and z) on three-dimensional computed tomography scans was used to compare the positional change between the surgical methods. The paired t-test, Wilcoxon text, and independent t-test were used in data analysis, and statistical analysis was performed using SPSS 23.0 software.

RESULTS

Medial and superior movement of the freed malar arch segment was significantly different between AR and SR (P < 0.05). Although medialization and superiorization were not significantly different between AR and SR, there was a significant difference in anterior-posterior movement between AR and SR (P < 0.05).

CONCLUSION

The radiologic analysis based on malar arch movement between AR and SR showed similar narrowing effects on medialization and superiorization of the malar arch regardless of bony resection. Therefore, the AR can be effectively applied in case of arch dominant type or malar asymmetry. In addition, further comprehensive study including analysis on movement of facial soft tissue following malar bony movement is expected based on this study in near future.

[The feasibility of zygomatic implant quad approach in patients with tooth agenesis: a radiographic analysis]

PURPOSE

The aim of this study was to analyze the feasibility of zygomatic implant quad approach in patients with tooth agenesis.

METHODS

Based on the data from cone-beam CT (CBCT), twenty one patients with tooth agenesis who were planned to receive zygomatic implant quad approach were enrolled. The radiographic bone-to-implant contact (rBIC) of each zygomatic implant placed virtually in patients' zygomatic segment was measured. SPSS 25.0 software package was used for statistical analysis.

RESULTS

Twenty patients' plans of zygomatic implant quad approach were completed (12 men and 8 women). A total of 80 zygomatic implants were placed virtually and the average rBIC of zygomatic segment was (13.85±3.29) mm. The rBIC values of 40 mesial zygomatic implants and 40 distal zygomatic implants were (13.80±3.74) mm and (13.90±2.81) mm, respectively(P>0.05). The average rBIC in male of 24 mesial zygomatic implants and 24 distal zygomatic implants were(14.21±4.08) mm and(14.31±3.18) mm, respectively, slightly higher than those in female of 16 mesial zygomatic implants and 16 distal zygomatic implants, which were (13.18±3.18) mm and (13.29±2.10) mm, respectively. There was no significant difference between the two groups (P>0.05). The average rBIC of 15 extra sinus zygomatic implants, 46 against sinus lateral wall zygomatic implants and 19 intra-sinus zygomatic implants were (16.27±2.95), (13.87±3.10) and (11.88±2.78) mm, respectively. There was significant difference between the extra sinus zygomatic implants and the other two(P<0.05).

CONCLUSIONS

It is feasible to plan zygomatic implant quad approach for patients with tooth agenesis. Zygomatic implants can get adequate rBIC in zygomatic segment and to provide sufficient support and retention of the superstructure.

The Use of Inferior Meatal Antrostomy to Decrease Sinusitis with the Placement of Zygomatic Implants

PURPOSE

To present a case series treated by inferior meatal antrostomy as a prophylactic maneuver after the placement of zygomatic implants to decrease the risk of sinusitis.

MATERIALS AND METHODS

All patients undergoing zygomatic implant placement using the lower meatal antrostomy protocol between June 2011 and March 2019 at the Department of Oral and Maxillofacial Surgery, Universidad El Bosque, were included. Patients were evaluated after 12 months of the procedure using clinical and radiologic criteria described by Kuriyama and Reiskin.

RESULTS

Forty-eight patients were included, in whom 184 implants were placed. Complications were as follows: paresthesia (6.2%), orosinusal fistula (4.1%), skin infection (2.1%), and loss of the implant (1.6%). There were no cases of sinusitis.

CONCLUSION

This study provides evidence that the technique is effective and should be considered because of its simplicity. The inferior meatal antrostomy has been proven to be a simple, effective, and reliable technique to decrease the risk of sinusitis associated with the placement of zygomatic implants.

Zygomatic implants supported rehabilitations in atrophic maxilla: sinus complications, radiological, periodontal and prosthodontic evaluations: a one year follow up retrospective longitudinal study

The rehabilitation of maxillary bone atrophy represents one of the main challenges of modern oral implantology. The use of zygomatic implants in the prosthetic rehabilitation of the patient affected by severe maxillary bone atrophy is another therapeutic alternative, not exempt from complications. The present study included 19 patients with edentulous maxillae who were treated between 2013 to 2015 with at least two zygomatic implants at the Department of Maxillofacial Surgery, Verona, Italy. The purpose of this retrospective longitudinal study was to evaluate sinus complications and radiological, periodontal and prosthetic evaluations of zygomatic implants technique in severe atrophic. Implant-prosthetic rehabilitation of the upper jaw edentulous severely atrophic using zygomatic implants represents one safe and repeatable technique. In terms of implant survival from our study showed an implant CRS (common reporting standard) of 98.5% and a prosthetic CRS 100% with a mean follow-up period of 19.2 months (range). Both recorded data are superimposed on major reported studies in literature.

Osteomyelitis of frontal sinus, zygomatic bone and maxilla

A 52-year male patient reported with loosening of right upper jaw. He has no pain or discharge, or any acute symptoms and systemic disease. Intraoral examination reveals necrosed maxillary bone. He also has no sickle cell disease, hepatitis, HIV or tuberculosis. 3D CT scan reveals destruction of maxilla, maxillary sinus, lateral nasal wall, superior and inferior orbital wall, zygoma and frontal bone(outer table). The clinical diagnosis of osteomyelitis was made. Under general anaesthesia, sequestrectomy was done with the help of Weber-Ferguson incision with infraorbital extension for maxilla, maxillary sinus, zygomatic bone, lateral nasal wall and infraorbital and medial wall of orbit. Frontal sinus region sequestrectomy was done via bicoronal flap. The patient was completely diseased free after 4 years follow-up.

Zygomatic root abscess: A rare entity not to be forgotten!

Zygomatic root abscess is a rare extracranial extratemporal complication of otitis media. To the best of our knowledge, there are only a few scattered cases of zygomatic root abscesses reported in the literature. We present an unusual case of a zygomatic root abscess in a 24 years old adult. He presented with one month duration of right zygomatic swelling. Otoscopic examination revealed superior and posterior external auditory canal wall sagging with an intact tympanic membrane. High Resolution Computed Tomography (HRCT) temporal bone revealed a rim enhancing lesion lateral to the zygomatic process with fluid filled mastoid air cells. He was managed with antibiotics and staged surgical interventions. He recovered well. Our case serves to shed light on the pathways of infection, clinical manifestations and timely staged surgical intervention in this rare pathology.

Computer-guided contouring of craniofacial fibrous dysplasia involving the zygoma using a patient-specific surgical depth guide

The aim of this study was to introduce a new computer-guided technique for contouring and shaving of craniofacial fibrous dysplasia involving the zygoma. Computer-guided contouring was performed for five patients with unilateral craniofacial fibrous dysplasia involving the zygoma, using a patient-specific surgical depth guide. This patient-specific guide with depth holes was virtually designed for each patient based on mirroring of the unaffected side. The guide was printed using rapid prototyping. In the surgical theatre, the guide was seated in place and implant drills were inserted through the guide holes, creating depth holes according to the preoperative planning. Bone removal was then continued using surgical burs and/or bone chisels, connecting the guiding depth holes. Satisfaction with facial aesthetics was evaluated by the patients using a Likert scale, and by the surgeons using the Whitaker rating scale. All patients were satisfied with the postoperative facial aesthetics. Four patients were rated category I on the Whitaker rating scale, and one patient as category II. In conclusion, this patient-specific surgical depth guide appears to offer a solution for the unpredictability of conventional bone removal in unilateral craniofacial fibrous dysplasia, especially in three-dimensional multiplanar areas such as the zygoma. Further investigations are required.

Maxillary Cortical Bone Thickness in a South-Eastern Anatolian Population: A Cone-Beam Computed Tomography Study

BACKGROUND The aim of this study was to measure the distance between the maxillary premolar and molar teeth apices to the buccal cortical bone and evaluate differences in gender and age group, using cone beam computed tomography (CBCT). MATERIAL AND METHODS This retrospective study comprised of 451 premolar and molar teeth of one hundred and thirteen patients who were admitted to Dicle University, Faculty of Dentistry, Department of Dentomaxillofacial Radiology for different reasons. Data were analyzed using Student's t-tests and Tukey HSD tests. RESULTS There was significant difference in buccal bone thickness by gender (p<0.05). The thinnest point of the maxillary buccal bone was measured in women as 2.11 mm and in men as 2.02 mm in the first premolar teeth. The thickest point of maxillary buccal bone was measured in women as 9.87 mm and in men 10.71 mm palatinal root of the first molar. A comparison of buccal bone thickness between age showed a statistically significant difference at the distobuccal and palatinal roots of the first molar, at the mesiobuccal root of the second molar (p<0.05). CONCLUSIONS The measurements of maxillar buccal bone thickness using CBCT for various dental procedures especially in endodontic surgery, orthodontic mini implant treatment, dental implant procedures, and healing after tooth extraction that are important knowledge.

Bone and cortical bone thickness of mandibular buccal shelf for mini-screw insertion in adults

OBJECTIVE

To analyze the buccal bone thickness, bone depth, and cortical bone depth of the mandibular buccal shelf (MBS) to determine the most suitable sites of the MBS for mini-screw insertion.

MATERIALS AND METHODS

The sample included cone-beam computed tomographic (CBCT) records of 30 adult subjects (mean age 30.9 ± 7.0 years) evaluated retrospectively. All CBCT examinations were performed with the i-CAT CBCT scanner. Each exam was converted into DICOM format and processed with OsiriX Medical Imaging software. Proper view sections of the MBS were obtained for quantitative and qualitative evaluation of bone characteristics.

RESULTS

Mesial and distal second molar root scan sections showed enough buccal bone for mini-screw insertion. The evaluation of bone depth was performed at 4 and 6 mm buccally to the cementoenamel junction. The mesial root of the mandibular second molar at 4 and 6 mm showed average bone depths of 18.51 mm and 14.14 mm, respectively. The distal root of the mandibular second molar showed average bone depths of 19.91 mm and 16.5 mm, respectively. All sites showed cortical bone depth thickness greater than 2 mm.

CONCLUSIONS

Specific sites of the MBS offer enough bone quantity and adequate bone quality for mini-screw insertion. The insertion site with the optimal anatomic characteristics is the buccal bone corresponding to the distal root of second molar, with screw insertion 4 mm buccal to the cementoenamel junction. Considering the cortical bone thickness of optimal insertion sites, pre-drilling is always recommended in order to avoid high insertion torque.

Quantitative analysis of the trajectory of simulated basilar apex aneurysms through the internal carotid artery to assess the need for an orbitozygomatic approach

Background

The aim of this study was to identify the correlation between the location of the internal carotid artery (ICA) and the need for an orbitozygomatic approach (OZA) when approaching a basilar apex (BX) aneurysm.

Materials and methods

By imaging the virtual trajectory to access the basilar artery (BA) through the ICA, the correlations among the height of the BX, the height and lateral breadth of the bifurcation of the ICA, and the need for removal of the orbital rim or zygomatic arch were investigated using three-dimensional computed tomography angiography (3DCTA) data of approximately 80 random samples not limited to BX aneurysms. Furthermore, the utility of 3D simulation to determine the need for the OZA was verified using data from five patients with BX aneurysms.

Results

The height of the bifurcation of the ICA was inversely correlated and the height of the BX was positively correlated with the need for the OZA (both p < 0.017). Among patients undergoing surgery, clipping was successfully performed without the OZA in two patients in whom the distance from the simulated skull point on the extended line from the BX through the bifurcation of the ICA was more than 4 cm from the zygoma and orbital rim.

Conclusions

It is necessary to determine the spatial relationship between the basilar artery and the ICA to decide whether the OZA is needed for surgery. Correlations of the height of the ICA and BX with the need for the OZA were not very strong individually, though they were significant. Therefore, simulation using 3DCTA appears to be important for planning the surgical approach for the treatment of BX aneurysms.

Comparison and reproducibility of 2 regions of reference for maxillary regional registration with cone-beam computed tomography

INTRODUCTION

The aims of this study were to evaluate the differences between 2 regions of maxillary voxel-based registration and to test the reproducibility of the registration.

METHODS

Three-dimensional models were built for before-treatment (T1) and after-treatment (T2) based on cone-beam computed tomography images from 16 growing subjects. Landmarks were labeled in all T2 models of the maxilla, and voxel-based registrations were performed independently by 2 observers at 2 times using 2 reference regions. The first region, the maxillary region, included the maxillary bone clipped inferiorly at the dentoalveolar processes, superiorly at the plane passing through the right and left orbitale points, laterally at the zygomatic processes through the orbitale point, and posteriorly at a plane passing through the distal surface of the second molars. In the second region, the palate and infrazygomatic region had different posterior and anterior limits (at the plane passing through the distal aspects of the first molars and the canines, respectively). The differences between the registration regions were measured by comparing the distances between corresponding landmarks in the T2 registered models and comparing the corresponding x, y, and z coordinates from corresponding landmarks. Statistical analysis of the differences between the T2 surface models was performed by evaluating the means and standard deviations of the distances between landmarks and by testing the agreement between coordinates from corresponding landmarks (intraclass correlation coefficient and Bland-Altman method).

RESULTS

The means of the differences between landmarks from the palate and infrazygomatic region to the maxillary region 3-dimensional surface models at T2 for all regions of reference, times of registrations, and observer combinations were smaller than 0.5 mm. The intraclass correlation coefficient and the Bland-Altman plots indicated adequate concordance.

CONCLUSIONS

The 2 regions of regional maxillary registration showed similar results and adequate intraobserver and interobserver reproducibility values.

Bone Resection Versus Setback in Reduction Malarplasty: A Quantitative Analysis of the Migration of the Summit of the Zygoma

BACKGROUND

We hypothesized that the amount of bone resection and setback together controls the effect of reducing the zygomatic body during reduction malarplasty; however, quantitative analyses of this movement are lacking.

METHODS

A retrospective study of patients who underwent reduction malarplasty between Aug. 2013 and Jan. 2015 was performed. We used 3-dimensional computed tomography (3D CT) scanning to measure movements of the summit of the zygoma (SOZ). We analyzed 394 zygomas in 197 patients.

RESULTS

The bone resection amount was not significantly correlated with the anteroposterior movement of the SOZ (p = 0.270); in contrast, the setback amount, was significantly correlated with anteroposterior SOZ movement (p < 0.001). The bone resection amount was not correlated with cephalocaudal movement (p = 0.158); however, cephalocaudal movement was significantly correlated with the setback amount (p < 0.001). Both the bone resection amount and the setback amount were correlated with mediolateral movement (p < 0.001). The amount of bone resection determined the mediolateral movement. Both the bone resection amount and the setback amount were correlated with the mean movement distance of the SOZ (p < 0.001). Both the R (2) (0.704 > 0.084) and β (0.839 > 0.290) values indicated that the setback amount made a larger contribution to the SOZ movement distance than did the bone resection amount.

CONCLUSIONS

Whereas bone resection was the major factor in the medial movement of the SOZ, bone setback was the major factor in the anterior and superior movement of the SOZ and a minor factor in the medial movement. The results indicate that both bone reposition and bone resection are important factors in maximizing surgical results of the reduction malarplasty.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Reduction of isolated zygomatic arch fractures using dental instrument: Report of 2 cases and review of the literature

To assess the effectiveness of a dental instrument for reduction of isolated zygomatic arch fractures. Two patients were admitted to our clinic representing isolated unilateral zygomatic arch fracture. The common presenting complaints were pain, swelling and difficulty in mouth opening. Fractures were confirmed with plain radiography and computerized tomography. The fractures were reduced with upper buccal sulcus approach by dental instrument. Patients achieved satisfactory maximum mouth opening within 10 days. At follow up after 6 months, there was complete healing without any complication. This procedure is cost effective, time saving, safe and effective to manage isolated zygomatic arch fractures under local anaesthesia with satisfactory outcomes.

[Zygomatic localization of Langerhans cell histiocytosis - a case report]

Langerhans cell histocytosis is a rare disease. LCH is reported mainly in children aged less than 15 years, however it may appear at any age. In this work, the case of 17-month boy is reported. The boy was admitted to the pediatric ophthalmology department in order to diagnose the swelling and bruising in the lower part of left orbit, which had lasted for one month before. The clinical status, various imaging techniques' results (MRI, TK and PET) and immunohistochemistry led to the final diagnosis of multisystem LCH (spread to masticator muscle and zygomatic bone). After the pharmacological therapy the total remission was achieved. Since four years the child is regularly controlled by oncologists and hematologists with no relapse reported.

Asymptomatic chronic rhinosinusitis and osteitis in patients treated with multiple zygomatic implants: a long-term radiographic follow-up

PURPOSE

The aim of this study was to investigate implant survival and the reactions of the bone and mucosa of the maxillary sinuses in patients treated with fixed dental prostheses supported by multiple zygomatic implants.

MATERIALS AND METHODS

Between 2001 and 2007, patients with extensive resorption of the basal bone of the maxilla received multiple zygomatic implants without grafts. In 2012, the maxillary sinuses were examined with cone beam computed tomography. Neo-osteogenesis at the posterior wall of the sinus was considered to be a sign of osteitis and classified as mild (3 to 4 mm), moderate (4 to 5 mm), or severe (> 5 mm). The maxillary ostium was examined and accessory ostia were registered. The sinus mucosa was evaluated according to the Lund-Mackay staging system, and the sinus was checked for fluid level and atelectasis. Patients reported any nasal- and sinus-related symptoms.

RESULTS

Fourteen patients who had received 58 zygomatic implants and 13 standard implants were examined. The mean follow-up was 9.3 years, and the implant survival rates were 97% and 92% for zygomatic and standard implants, respectively. Osteitis was found in all but one patient and classified as severe in 17 of the 27 investigated sinuses. The infundibulum was obstructed in nine sinuses, and an accessory ostium was present in seven. The mucosa of the maxillary sinus showed signs of chronic rhinosinusitis in all but one patient. No fluid levels were observed. Atelectasis occurred in 15 sinuses. Twelve patients reported unaltered nasal and sinus status.

CONCLUSION

Patients with extensive bone resorption in combination with voluminous maxillary sinuses and nasal cavities can experience long-term success with prostheses supported by multiple zygomatic implants. Asymptomatic chronic rhinosinusitis with osteitis and gradual collapse of the maxillary sinus cavity can be anticipated.

Rare case of isolated osteochondroma of the zygomatic bone: an endoscopic-assisted approach

AIM

Osteochondroma is a benign neoplasia that in the craniofacial district unfrequently can occur in the coronoid process and in the zygomatic arch. We describe a rare case of isolated osteochondroma of the zygomatic bone, undergoing surgical treatment by means of intraoral approach and endoscopic assistance.

MATERIAL OF STUDY

A Caucasian woman aged fifty-two, has been observed in our Department on March 2012 because of pain in the right zygomatic area. Computed tomography (CT) scans of the right zygomatic bone showed an undefined, sessile lesion with lobar bounds (Fig. 2). Suspected diagnosis was osteochondroma. Surgery was planned via intraoral approach under general narcosis. The procedure was endoscope-assisted. The lesion was removed by using an endoscopic rotating cutter.

RESULTS

No edema, pain or fever occurred during the immediate recovery period. The patient has been followed up for 16 months and she is still actually lesion and symptoms free.

DISCUSSION

The use of endoscopy in the surgical treatment of this pathology has allowed to obtain a higher accuracy and a greater respect of the anatomic structures

CONCLUSIONS

In literature are not reported other cases of isolated zygomatic osteochondroma treated with endoscopicassisted procedures. Intraoral approach grants no scarring; endoscopic aid gives a better view of all anatomical structures of this district, a good management of the pathology and minimize the risk of pathological fractures during intraoperative procedures.

KEY WORDS

Endoscopic-assisted surgery,Isolated osteochondroma, Zygomatic bone osteochondroma.

Analysis of Age-Related Changes in Asian Facial Skeletons Using 3D Vector Mathematics on Picture Archiving and Communication System Computed Tomography

PURPOSE

There are marked differences in facial skeletal characteristics between Asian and Caucasian. However, ethnic differences in age-related facial skeletal changes have not yet been fully established. The aims of this study were to evaluate age-related changes in Asian midfacial skeletons and to explore ethnic differences in facial skeletal structures with aging between Caucasian and Asian.

MATERIALS AND METHODS

The study included 108 men (aged 20-79 years) and 115 women (aged 20-81 years). Axial CT images with a gantry tilt angle of 0 were analyzed. We measured three-dimensional (3D) coordinates at each point with a pixel lens cursor in a picture archiving and communication system (PACS), and angles and widths between the points were calculated using 3D vector mathematics. We analyzed angular changes in 4 bony regions, including the glabellar, orbital, maxillary, and pyriform aperture regions, and changes in the orbital aperture width (distance from the posterior lacrimal crest to the frontozygomatic suture) and the pyriform width (between both upper margins of the pyriform aperture).

RESULTS

All 4 midfacial angles in females and glabellar and maxillary angles in males showed statistically significant decreases with aging. On the other hand, the orbital and pyriform widths did not show statistically significant changes with aging.

CONCLUSION

The results of this study suggest that Asian midfacial skeletons may change continuously throughout life, and that there may be significant differences in the midfacial skeleton between both sexes and between ethnic groups.

Maxillary molar intrusion with zygomatic anchorage in open bite treatment: lateral and oblique cephalometric evaluation

PURPOSE

We aimed to use lateral and oblique radiographs to evaluate dental and skeletal changes arising from maxillary molar intrusion with zygomatic anchorage in open bite patients.

METHODS

We conducted a pilot study including nine patients (six females and three males; mean age, 18.7 ± 5.1 years) with skeletal open bite treated with titanium miniplates for posterior dentoalveolar intrusion. Lateral and oblique (right and left, 45°) radiographs were obtained before (T1) and 6 months after intrusion (T2). A paired t test was used for statistical evaluation.

RESULTS

The maxillary posterior teeth were intruded 2.03 ± 0.87 mm (p < 0.01) with 450×g of force, which resulted in counterclockwise rotation of the mandible (1.57°, p = 0.02) and clockwise rotation of the occlusal plane (4.27 ± 2.66°, p = 0.01). Anterior facial height decreased by a mean of 1.79 ± 1.51 mm (p < 0.01). No significant change in the palatal plane or in anteroposterior molar movement was observed.

CONCLUSION

The oblique radiograph at 45° was useful for the assessment of molar intrusion and anteroposterior displacement. The treatment of anterior open bite with skeletal anchorage provided intrusion of molars and counterclockwise rotation of the mandible, resulting in open bite closure.

Evaluation of 3-dimensional superimposition techniques on various skeletal structures of the head using surface models

Objectives

To test the applicability, accuracy, precision, and reproducibility of various 3D superimposition techniques for radiographic data, transformed to triangulated surface data.

Methods

Five superimposition techniques (3P: three-point registration; AC: anterior cranial base; AC + F: anterior cranial base + foramen magnum; BZ: both zygomatic arches; 1Z: one zygomatic arch) were tested using eight pairs of pre-existing CT data (pre- and post-treatment). These were obtained from non-growing orthodontic patients treated with rapid maxillary expansion. All datasets were superimposed by three operators independently, who repeated the whole procedure one month later. Accuracy was assessed by the distance (D) between superimposed datasets on three form-stable anatomical areas, located on the anterior cranial base and the foramen magnum. Precision and reproducibility were assessed using the distances between models at four specific landmarks. Non parametric multivariate models and Bland-Altman difference plots were used for analyses.

Results

There was no difference among operators or between time points on the accuracy of each superimposition technique (p>0.05). The AC + F technique was the most accurate (D<0.17 mm), as expected, followed by AC and BZ superimpositions that presented similar level of accuracy (D<0.5 mm). 3P and 1Z were the least accurate superimpositions (0.79<D<1.76 mm, p<0.005). Although there was no difference among operators or between time points on the precision of each superimposition technique (p>0.05), the detected structural changes differed significantly between different techniques (p<0.05). Bland-Altman difference plots showed that BZ superimposition was comparable to AC, though it presented slightly higher random error.

Conclusions

Superimposition of 3D datasets using surface models created from voxel data can provide accurate, precise, and reproducible results, offering also high efficiency and increased post-processing capabilities. In the present study population, the BZ superimposition was comparable to AC, with the added advantage of being applicable to scans with a smaller field of view.

Zygomatic arch reduction and malarplasty with multiple osteotomies: its geometric considerations

BACKGROUND

The midfacial width is dominated by the lateral protruding degree of the zygomatic arch. The best way of narrowing the midface is to reduce the arch height and the arc length for patients with an overly curved lateral protruding zygomatic arch. The existing techniques for reduction malarplasty cannot change the degree of curvature of the zygomatic arch. We provide a new technique for efficient midfacial width reduction by multiple osteotomies at different sites on the zygomatic complex and bone resection at the most protruding middle part of the zygomatic arch. The amount of bone resection can be calculated with a simplified geometrical solution according to the desired reduction rate of the arch height.

METHODS

A digitalized CT image was used to estimate the arch height and the length of bone for removal from the zygomatic arch. A specific piece of bone was removed from the most protruding point of each zygomatic arch. Greenstick fractures were made at the anterior and posterior roots of the zygomatic arch. The open arches were rotated inwardly until both ends met.

RESULT

The arch heights of 1,020 sides of the zygomatic arch were reduced in a range from 3 to 11 mm. All the reduced zygomatic arches were reunited properly and healed solidly. The overall satisfaction rate was high.

CONCLUSION

This technique reduces the width of the midface by changing the degree of curvature of the zygomatic arch. The simplified geometrical calculation solutions are helpful in assuring the reunion of the zygomatic arch at a pre-designed lower arc height level after a calculated shortening of the arc length.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

The reliability of using postero-anterior cephalometry and cone-beam CT to determine transverse dimensions in clinical practice

AIM

This study primarily aimed to assess the accuracy of classically-advocated reference points for the measurement of transverse jaw-base and dental relationships using conventional Postero-Anterior Cephalometry (PAC) and Cone-Beam Computed Tomography (CBCT).

METHOD

PAC and CBCT images were collected from 31 randomly selected orthodontic patients (12 males, 19 females), all of whom had a full permanent dentition. The transverse widths of the maxilla, mandible and the dentition were measured using reference points on both image modalities. Confidence intervals, intra-class coefficients and Bland Altman plots were used to assess the measurement differences derived from the two acquirement methods.

RESULTS

Measurements on PAC and CBCT images demonstrated statistically significant differences in the majority of the assessed variables. The interjugal (J-J) width was one of only two variables which did not demonstrate a statistically significant difference on image comparison. The mean differences of the antegonial width (Ag-Ag) (-4.44mm, 95% CI -5.38 to -3.51) represented the greatest difference between the imaging techniques. The application of these points to a transverse skeletal analysis (J-J/Ag-Ag ratio) revealed that five of the 31 subjects (16%) recorded 'false positive' readings according to the derived data.

CONCLUSION

It is recommended that clinicians are cautious when interpreting and making decisions related to transverse dimensions derived from a PAC. The PAC has a higher tendency to falsely identify individuals who require maxillary expansion procedures based on conventional clinical criteria. The errors primarily associated with identifying structures which represent the width of the mandible are significant in both PAC and CBCT techniques and require further investigation. It is postulated that the confounding effects of overlying soft tissues have a sianificant impact on a clinician's ability to identify relevant landmarks.

Comparison of pharyngeal airway volume among different vertical skeletal patterns: a cone-beam computed tomography study

OBJECTIVE

To test the null hypothesis that there are no significant differences in pharyngeal airway volumes among adult patients with different vertical skeletal patterns and a clinically normal sagittal skeletal pattern using cone-beam computed tomography (CBCT).

MATERIAL AND METHODS

The study sample consisted of 100 adult patients (45 men and 55 women; mean age  =  24.0 ± 5.3 years) with a normal sagittal skeletal pattern divided into three groups according to the vertical skeletal patterns: high angle (32 patients: 15 women and 17 men), low angle (34 patients: 14 women and 20 men), and normal angle (34 patients: 16 women and 18 men) groups. Nasopharyngeal, oropharyngeal, and total airway volumes of patients in all vertical groups were calculated. Group differences were analyzed using one-way analysis of variance and post hoc Tukey tests.

RESULTS

Nasopharyngeal airway volume in the high-angle group (mean  =  6067.9 ± 1693.9 mm(3)) was significantly lower than that of the low- and normal-angle groups (P < .01). Oropharyngeal airway volume was highest in the low-angle group (mean  =  15,957.6 ± 6817.2 mm(3)) and significantly decreased in the control (mean  =  11,826.1 ± 4831.9 mm(3); P  =  .008) and high angle (mean  =  10,869.1 ± 4084.1 mm(3); P  =  .001) groups. Total airway volume was highest in the low-angle group (mean  =  24,261.6 ± 8470.1 mm(3)) and lowest in the high-angle group (mean  =  16,937.0 ± 5027.4 mm(3); P < .001).

CONCLUSION

The null hypothesis was rejected. Significant differences were found in pharyngeal airway volumes among different skeletal vertical patterns.

An assessment of the maxilla after rapid maxillary expansion using cone beam computed tomography in growing children

INTRODUCTION

With the advent of cone beam computed tomography (CBCT), it is now possible to quantitatively evaluate the effects of rapid maxillary expansion (RME) on the entire maxillary complex in growing patients.

OBJECTIVE

The purpose of this study is to use three-dimensional images to evaluate the displacement that occurs at the circummaxillary sutures (frontonasal, zygomaticomaxillary, intermaxillary, midpalatal, and transpalatal sutures) following rapid maxillary expansion in growing children.

METHODS

The CBCT scans of 25 consecutively treated RME patients (10 male, 15 female) with mean age of 12.3±2.6 years, were examined before expansion and immediately following the last activation of the expansion appliance.

RESULTS

Statistically significant (P<0.05) amounts of separation were found for the displacement of the bones of the frontonasal suture, the intermaxillary suture, the zygomaticomaxillary sutures, and the midpalatal suture. The change in angulation of the maxillary first molars due to RME was also statistically significant. There was no statistically significant displacement of the transpalatal suture.

CONCLUSIONS

Rapid maxillary expansion results in significant displacement of the bones of circummaxillary sutures in growing children.

Unusual anatomical detection of a third molar in the infratemporal fossa

Third molar presence in the infratemporal fossa is a rare event and it has been reported previously only two times in the literature, except for the cases which arise from complications occurring during the extraction of the impacted upper third molar. Due to the presence of important vessel bundles and nerves in this area, third molar removal requires a correct surgical management in order to avoid many possible serious side effects. We report an unusual case of upper third molar detected in the infratemporal fossa, which has been thoroughly investigated radiologically and removed through a safe surgical approach.

The buccal fat pad flap: an option to prevent and treat complications regarding complex zygomatic implant surgery. Preliminary report

PURPOSE

To evaluate the use of the buccal fat pad flap (BFPF) technique as an option to prevent complications in the treatment of patients with atrophic maxillae rehabilitated after complex zygomatic implant surgery.

MATERIALS AND METHODS

A retrospective study was made of completely edentulous patients submitted to zygomatic implant surgery between May 2005 and November 2007. Patients with severely atrophic maxillae received conventional and zygomatic implants and were followed after the implants were loaded. Preoperative evaluation included panoramic radiography and computed tomographic scans of the maxilla to identify the anatomic conditions and presence of pathology.

RESULTS

Eight male patients with a mean age of 57 years and atrophic maxillae were rehabilitated with zygomatic implants placed using the BFPF technique. The BFPF technique was used in complex situations, including oroantral communication-associated sites, areas that had lost the sinus wall, and extrasinus implant placement. A total of 16 conventional implants, 4 long (21-mm) tilted implants, and 22 zygomatic implants was placed. The patients were rehabilitated with fixed prostheses and were followed for a minimum of 15 months. None of the conventional implants failed and none of the zygomatic implants failed or presented with soft tissue complications.

CONCLUSION

The BFPF presented a high success rate, demonstrating that it is a viable and predictable treatment option to prevent and treat soft tissue complications in complex zygomatic implant surgery.

Imaging and histopathological features of Jacob's disease: a case study

A pathologically elongated coronoid process forming a joint with the zygomatic arch and bone is termed as "Jacob's disease." Herein, we present a case of Jacob's disease, which has rarely been reported in the literature. Moreover, very few cases have been reported from the Indian subcontinent. A 28 years-old male reported to us with progressive restriction of mouth opening. After detailed imaging, coronoidectomy was performed through an intraoral approach. A mushroom-shaped gross specimen was obtained. Osteochondroma of the coronoid process was diagnosed based on the histopathologic examination of the excised tissue. Although Jacob's disease is seldom considered in the list of differential diagnoses for restricted mouth opening, our case highlights the need for evaluation of the coronoid process, which is usually ignored during routine radiographic examination. The report also highlights the miniscule incidence of this condition in the available literature.

Surgical management of primary chronic osteomyelitis of the jaws in children: a prospective analysis of five cases and review of the literature

INTRODUCTION

Primary chronic osteomyelitis (PCO) of the jaws is an uncommon non-suppurative inflammatory disease of unknown origin. Although the disease is not age-specific, only sparse cases with onset during childhood or adolescence have been reported in the literature.

PURPOSE

This study seeks to present five cases of maxillofacial PCO in children and to evaluate the effectiveness of the applied therapeutic protocol. A review of the literature concerning diagnosis and treatment of PCO with special emphasis on surgical therapy is also performed.

PATIENTS AND METHODS

Demographic data, clinical, radiographic and histopathologic findings, blood tests results, and the treatment protocol applied to five young patients suffering from PCO and referred to the Department of Oral and Maxillofacial Surgery at "A. & P. Kyriakou Children's Hospital" over the past 5 years are presented. Decortication and contouring of the affected bone were performed; antibiotics were administered for a short period of time and the patients remained under follow-up evaluation.

RESULTS

The posterior mandible was affected in four cases and the maxilla-zygomatic bone in one case. All patients showed remission of signs and symptoms after surgical treatment. The postsurgical clinical course was uneventful in all cases. However, recurrences have been noted, as reported in the literature.

CONCLUSION

PCO of the jaws is a complex clinical entity, presenting both a diagnostic and therapeutic challenge, especially in young patients. Surgical treatment in conjunction with antibiotics and non-steroid anti-inflammatory drugs proved to be beneficial and to improve considerably the patients' quality of life. Nevertheless, exacerbation of the disease may appear and regular follow-up of the patients is required.